METHOD OF PRESERVING LEPIDOPTERA.

PREPARED FOR THE SMITHSONIAN INSTITUTION BY TITIAN R. PEALE.

THE difficulties in the preservation of zoological collections generally arise from two causes, namely, moisture and destructive insects.

To guard against the effects of moisture requires so little ingenuity that I shall merely allude incidentally to the necessity of drying the specimens well at first, and then keeping them in dry places.

The greatest of all difficulties to guard against, particularly in this country, is the voracity of the destructive insects belonging to the entomological families of Dermestida and Tineida. These are the worst enemies of the zoological curator, as well as the fur-trader and careful housewife.

Tinea tapetzella, the clothes moth, which troubles the housewife and the clothier, does not disturb the entomologist; consequently the whole of this family may here be passed by in silence.

Dermestes lardarius (the bacon beetle) and Anthrenus musæorum (museum beetle) and their congeners are the great depredators. In the time of the Pharaohs of Egypt they destroyed the mummies which were intended to last through all time, and now in our day they destroy the specimens with which we hope to enlighten posterity. As they have been known for centuries, numerous poisons and various devices have been resorted to in order to destroy them, but they remain as numerous as ever, being naturalized and abundantly propagated wherever man has made his resting-place on the earth.

In early life I was a devoted student of nature, an industrious collector of specimens, and a somewhat expert taxidermist. It is, however, needless to record the fact that I lost my specimens, like others, almost as fast as they were collected, and, as a last resource, I was compelled to undertake a careful study of the habits of the enemies with which I had to contend, in order to learn the means of subduing them. I early found that substances containing albumen or gelatine stand but little chance of escaping the ravages of the Dermestidæ, and must be destroyed, sooner or later, by their attacks, whether moist or dry, unless chemically changed in character, or kept by some mechanical arrangement beyond the reach of the insect. I say chemically altered, because, as in the case of gelatine soaked in corrosive sublimate, the coagulation of the material, which is a chemical change, so alters the matter as to render it no longer a proper food for the insect. The means of protecting, therefore, must be adapted to the kind of specimens to be preserved. Our present object is principally to describe a successful experiment in preserving Lepidoptera, and to this subject we shall chiefly confine our remarks.

The vapor of camphor, and the essential oils generally, are sickening or fatal to the perfect insects of the family Dermestidæ, but have little or no effect upon their eggs or larvæ; consequently, although these perfumes in close cases are useful to keep out the parent insects, they will not destroy the progeny after a lodgement has once been attained. The several species of this family, unlike most other insects, have no fixed period or season for depositing their eggs, and consequently require to be vigilantly guarded against at all times. They are about one year in attaining their full growth, in which time they cast their skins four or five times. Their feet, though armed with claws, are unfit to climb on a hard smooth substance like that of clean polished glass. They spin no silk, and therefore cannot, like many caterpillars, construct a fibrous ladder to climb

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up the same surface. Upon these simple facts I based plans for the preservation of Lepidoptera as long ago as 1828, and since then no specimen which I have wished to preserve has been touched by Dermestes.

For collecting insects I have generally found the case described by LeValliant, during his travels in South Africa, the most convenient. This principally consists of a box filled with perpendicular slides covered with cork, to which the specimens are pinned, and a horizontal drawer at the bottom to receive any specimens which may be disengaged from the slides during transportation, and thus preventing it from damaging those which remain on the slide. The spaces between the slides being all open below, a single bag of camphor placed in the drawer will diffuse its vapor through all the compartments, and thus prevent the attack of ants, roaches, and other large insects which prey, especially in tropical countries, on the fresh specimens. By placing the specimens on the perpendicular slides, tile-fashion, I have found that double the number could be accommodated, while additional security was gained by this arrangement from the danger of the loosening of the pins by the jolting of the box.

In the preparation for the cabinet I begin by pinning the specimens to be preserved in the order in which they are finally to be preserved on the bottom of a shallow box, lined with a thin layer of cork, or, better, of balsa-wood, which is easier penetrated by the point of the pin. This box must be of precisely the same length and breadth as those which are to form the permanent cases of the cabinet. When the specimens have been ar

ranged in the order to suit the taste, and so that one may not overlap the other, the box, with its contents, is transferred to an oven, which I also invented in 1828 for this special object, but which has since been used, generally by chemists and others, for a variety of purposes. It is surrounded and heated by boiling water, the temperature of which is sufficient to kill the eggs and the larvæ of the Dermestes, but is not sufficient to injure the specimens of butterflies, moths, &c. The specimens are kept in this oven several hours, or during the night. (See Fig. 1.)

Fig. 1.

After the specimens have been sufficiently baked I lay a clean pane of plate glass immediately over the specimens, which, resting on the perpendicular sides of the box, does not touch them. On the upper side of this glass plate, face down, and directly over the pin securing each specimen, I attach, with fish-glue, (isinglass,) a circular piece of paper, about a quarter of an inch in diameter, containing a printed number. The size of the glass plates which I use, and find most convenient, is eight and a half by ten and a half inches. It is commonly imported, and used for cheap mirrors. It must be cleaned with dilute nitric acid, or the surface will be liable to become foggy in damp changes of weather.

Next small cylinders of cork of the same diameter as the papers containing the numbers, and just large enough to support the specimens, are cemented to the glass plate directly on the top of each of the paper numbers. The cement used for this purpose is composed of about equal parts of resin, beeswax, and chrome green, melted, for convenience, over a nursery lamp placed on the table beside me. The pieces of cork are dipped into the composition, and while the portion of the latter which adheres is still liquid, they are attached to the glass. in their proper positions.

The next operation is to attach the plate glass to a wooden frame, thus forming a shallow box, of which the glass plate will be the bottom, having the numbers and cork supports on the inner side. This frame is made of strips of

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METHOD OF PRESERVING LEPIDOPTERA.

white pine, ready planed by the carpenter, to the dimensions of one inch and an eighth in width, and three sixteenths of an inch in thickness. These slips are cut to the proper length, and fastened in the form of a rectangle by common pins at the corners, as shown in Fig. 2. Previous, however, to forming the slips of wood into frames, they are coated on all sides with tinfoil, which is attached by means of the cement above described, omitting the coloring matter. I find it convenient to keep on hand while preparing these cases a supply Fig. 2. of tinfoil, coated on one side ready, when required, to be cut into slips of the proper size. The coating of cement is put on by means of a brush dipped into the melted material.

Another plan, and I believe the best one, is to have the cement enclosed in a muslin bag, which may be tied to the end of a short stick; the tinfoil is to be spread out on a hot iron plate, say the top of a stove, when the bag containing the cement is rubbed over its surface, and the heat being sufficient to melt the wax and resin, the foil may be evenly coated, and on removal from the hot metal plate, as it cools quickly, may then be rolled up and kept in readiness to be cut in suitable pieces for use.

b

Fig. 3 exhibits a box thus formed, of which a, b, c, d are the wooden sides covered with tinfoil, and e the glass plate, on the inside of which are placed the paper numbers covered by the cork supports. The next step Fig. 3. in the process is to transfer the butterflies in the preliminary box to their several supports on the glass plate, and to securely pin them to the cork so as not to fall off in the ordinary handling of the cabinet. After this the box is to be permanently closed with a glass cover of the same dimensions as the one which forms the bottom, and the whole fastened air-tight by means of the tinfoil. By this arrangement the specimens are hermetically sealed between two parallel panes of plate glass, which allow the under as well as the upper surfaces of the insect to be seen, while the whole is preserved from atmospheric changes and the ravages of insects.

The cases containing the specimens are now furnished, so far as the means of preserving the contents are concerned, but this case itself requires to be guarded

from injury and kept free of dust. For this purpose it is placed in an outer case, which I prefer to make in the form of a book with covers, which, on opening, exhibit the glass plates and the contents of the case. On the inner surfaces of these covers I write, or print, the names of the specimens therein contained.

All the cases which form the whole cabinet are arranged in an ordinary bookcase with glass doors, and when properly ornamented on the back resemble a series of large octavo volumes. The cases should always be kept like books in a case, in an upright position, and never allowed to lie on their sides, except when in use. The reason for this will be obvious: the perfect Dermestes might find a small hole in the tinfoil wherein to enter, or, deposit its eggs; but should the glass be upright, neither the old nor the young depredators would be able to climb up to the specimens, which they possibly might reach if the case should lie on its side.

Fig. 4.

Thirty-five years' experience with cases made as above described has proved the correctness of the theory of their construction.

AN ACCOUNT

OF

A REMARKABLE ACCUMULATION OF BATS.

BY M. FIGANIERRE É MORAO, MINISTER PLENIPOTENTIARY FROM PORTUGAL TO THE

IN the winter of 1859, having purchased the property known as Seneca Point, in the margin of the Northeast river, near Charleston, in Cecil county, Maryland, we took possession of it in May of the next year. The dwelling is a brick structure, covered with slate, in the form of an L, two storied, with garret, cellars, and a stone laundry and milk-house attached. Having been uninhabited for several years, it exhibited the appearance, with the exception of one or two rooms, of desolation and neglect, with damp, black walls, all quite unexpected, as it had been but very slightly examined, and was represented in good habitable condition, merely requiring some few repairs and a little painting.

The boxes, bundles, and other packages of furniture which had preceded us, laid scattered around and within the dwelling; these, with the exception of some mattresses and bedding for immediate use, were hastily arranged for unpacking and placing in order at leisure. The weather, which was beautiful, balmy and warm, invited us towards evening to out-door enjoyment and rest, after a fatiguing day of travel and active labor; but chairs, settees, and benches were scarcely occupied by us on the piazza and lawn, when, to our amazement and the horror of the female portion of our party, small black bats made their appearance in immense numbers, flickering around the premises, rushing in and out of doors and through opened windows, almost obscuring the early twilight, and causing a general stampede of the ladies, who fled, covering their heads with their hands, fearing that the dreaded little vampires might make a lodgement in their hair. This remarkable exhibition much increased our disappointment in regard to the habitable condition of our acquisition, and was entirely unexpected, inasmuch as the unwelcome neighbors were in their dormant state and ensconced out of sight when the property was examined previous to purchase. With their appearance, and in such immense numbers, the prospect of immediate indoor arrangement and comfort vanished; the paramount the urgent necessity was to get rid of such a nuisance as quickly as possible, and the question was by what means could this be accomplished. Our scientific friends and acquaintances both in New York and Philadelphia were consulted, various volumes of natural history were examined, in order to ascertain the peculiar habits of the vermin, but we derived no effectual consolation from these sources. One of our friends, indeed, sent us from New York an infallible exterminator in the form of a recipe obtained at no inconsiderable cost: strips of fat pork saturated with a subtle poison were to be hung up in places where the annoying "creatures did most congregate"-of this they would surely eat and thus shuffle off their mortal coil." How many revolving bat seasons it might have required by this process to kill off the multitude, the urgency of the case would not allow us to calculate, and the experiment was therefore abandoned.

66

Evening after evening did we patiently though not complacently watch this periodical exodus of dusky wings into light from their lurking-places one after

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A REMARKABLE ACCUMULATION OF BATS.

another, and in some instances in couples and even trebles, according as the size of the holes or apertures from which they emerged in the slate roofing would permit. Their excursions invariably commenced with the cry of the "whippoorwill" both at coming evening and at early dawn, and it was observed that they always first directed their flight towards the river, undoubtedly to damp their mouse-like snouts, but not their spirits, for it was likewise observed that they returned to play hide-and-seek and indulge in all other imaginable gambols; when, after gratifying their love of sport and satisfying their voracious appetites (as the absence of mosquitoes and gnats testified) they would re-enter their habitation, again to emerge at the first signal of their feathered trumpeter. I thus ascertained one very important fact, namely, that the bat, or the species which annoyed us, ate and drank twice in twenty-four hours. Such appeared their habit-such, therefore, was their indispensable need. Upon ascertaining this fact, after having tried suffocation by the fumes of brimstone with only partial success, I concluded to adopt a more efficient plan of warfare, and for this purpose commenced by causing all the holes, fissures in the wood-work, and apertures in the slating to be hermetically sealed with cement. This put a stop to their egress, but to avoid their dying by starvation and deprivation of water, which would much increase the annoyance by adding their dead to their living stench, Lordered apertures of about two feet square to be opened in the lathed and plastered partition on each side of the garret windows and also in the ceiling of every garret room; lastly, when the bat's reveille was sounded by the bugle of the whippoorwill, all the hands of our establishment, men and boys, each armed with a wooden implement, (shaped like a cricket-bat,) marched to the 47 { «_third-floor “on murderous deeds with thoughts intent;" a lighted lantern was placed in the middle of one of the rooms, divested of all furniture, to allure the hidden foe from their strongholds. After closing the window to prevent all escape into the open air, the assailants distributed themselves at regular distances to avoid clubbing each other, awaited the appearance of the bats, enticed into the room by the artificial light and impelled by their own natural craving. The slaughter commenced and progressed with sanguinary vigor for several hours, or until brought to a close by the weariness of dealing the blows that made the enemy bite the dust, and overpowered by the heat and closeness of the apartment. This plan succeeded perfectly. After a few evenings of similar exercise, in which the batteurs became quite expert in the use of their weapon every wielding of the wooden bat bringing down an expiring namesake, the war terminated by the extermination of every individual of the enemy in the main building. However, there still was the cock-loft of the laundry, which gave evidence of a large population. In this case I had recourse to a plan which had been recommended, but was not carried out in regard to the dwellinghouse. I employed a slater to remove a portion of the slating which required repairing. This process discovered some fifteen hundred or two thousand bats, of which the larger number were killed, and the surviving sought the barn, trees, and other places of concealment in the neighborhood.

In the main building nine thousand six hundred and forty bats, from actual counting, were destroyed. This was ascertained in the following manner: after the battling of each evening the dead were swept into one corner of the room, and in the morning, before removing them to the manure heap, they were carefully counted and recorded; many had been killed before and some few after the reckoning was made, and were not included in it, nor were those killed under the adjoining laundry roof. The massacre commenced by killing fewer the first evenings, the number increasing and then diminishing towards the end, but it was generally from fifty or a hundred, up to six hundred and fifty, the highest mortality of one evening's work, dwindling down to eight, five, three, and two. This species of bat is generally small, black, and very lively; some smaller han the ordinary size were found, probably young ones, and one or two larger,